Calcium silicate-based sealers remnants in isthmuses of mesial roots of mandibular molars: an in vitro evaluation.

Objectives: Endodontic retreatment aims to address treatment failure through the removal of root canal filling materials. This in vitro study evaluated the presence of filling material remnants in the mesial root canals, specifically focusing on the isthmuses, of mandibular molars after retreatment.

Methods: One hundred extracted mandibular molar mesial roots with isthmuses were prepared with an R25 file, obturated with one of five calcium silicate-based sealers (BioRoot RCS [Septodont], MTApex [Ultradent Products Inc.], EndoSequence BC Sealer HiFlow [Brasseler USA], Bio-C Sealer [Angelus]) or an epoxy resin-based sealer (AH Plus Jet [Dentsply Maillefer]), all stained with rhodamine B, and stored at 37ºC for 30 days to allow for setting. Retreatment was subsequently performed using R40 and XP-endo Finisher R instruments (FKG Dentaire) with 2.5% sodium hypochlorite irrigation. The presence of remaining filling material was then assessed using confocal microscopy, and setting times were tested per ISO 6876:2012.

Results: AH Plus Jet showed the most remnants at 2 mm and the longest retreatment time. Calcium silicate-based sealers exhibited prolonged setting times under dry conditions, with EndoSequence BC Sealer HiFlow showing a particularly extended setting period.

Conclusions: Despite retreatment, residues remained in all canals and isthmus regions, particularly Bio-C Sealer and AH Plus Jet in apical areas, emphasizing the difficulty of complete removal and the persistence of filling material.